title: Brain natriuretic peptide is stable in whole blood and can be measured using a simple rapid assay: implications for clinical practice.
abstract: OBJECTIVE
  To compare the stability of brain natriuretic peptide (BNP) to that of N-terminal atrial natriuretic peptide (NT-ANP) in whole blood and plasma stored under different conditions. To compare a rapid, simple, direct (unextracted) BNP assay to a conventional assay using plasma extraction.
  
  
  METHODS
  Blinded, prospective, comparative study.
  
  
  METHODS
  Tertiary referral cardiology department.
  
  
  METHODS
  Forty two subjects (24 men, 18 women) comprising 28 patients with left ventricular systolic dysfunction (LVSD) ranging from mild to severe and 14 healthy volunteers.
  
  
  METHODS
  Stability of NT-ANP and BNP when stored as whole blood or plasma at room temperature over three days. Reproducibility of measurements.
  
  
  RESULTS
  BNP was stable in whole blood stored at room temperature for three days; mean change in concentration -7.4% (95% CI 0.6 to -14.8), (direct), -6.3% (5.0 to -16.4), (extracted); whereas a significant decline in BNP concentration was noted in plasma stored at room temperature; -23.2% (-13.7 to -31.6), (direct); -14.4% (-3.2 to -24.3), (extracted). By contrast a small nonsignificant rise in NT-ANP concentration was noted both in whole blood and plasma stored at room temperature for three days; whole blood +8.6% (+22.3 to -3.5), plasma +6.3%, (23.2 to -8.4). The reproducibility of the BNP measurements, and particularly the rapid, direct, measurement, was superior to that for NT-ANP.
  
  
  CONCLUSIONS
  BNP is shown to be stable in whole blood for three days and can be measured using a rapid, simple assay. Routine assay of BNP is feasible in ordinary clinical practice and may be of value to general practitioners and hospital based physicians in the diagnosis and management of patients with LVSD. Samples can be sent to a central laboratory without special handling requirements.
authors.affiliation: Medical Research Council's Clinical Research Initiative in Heart Failure, University of Glasgow, UK.
authors.forename: D R
authors.initials: DR
authors.lastname: Murdoch
authors.forename: J
authors.initials: J
authors.lastname: Byrne
authors.forename: J J
authors.initials: JJ
authors.lastname: Morton
authors.forename: T A
authors.initials: TA
authors.lastname: McDonagh
authors.forename: S D
authors.initials: SD
authors.lastname: Robb
authors.forename: S
authors.initials: S
authors.lastname: Clements
authors.forename: I
authors.initials: I
authors.lastname: Ford
authors.forename: J J
authors.initials: JJ
authors.lastname: McMurray
authors.forename: H J
authors.initials: HJ
authors.lastname: Dargie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D009320:Atrial Natriuretic Factor / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain; D009419:Nerve Tissue Proteins / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D013599:Systole; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000097:blood*
chemical_list: D009419:Nerve Tissue Proteins; D020097:Natriuretic Peptide, Brain; D009320:Atrial Natriuretic Factor